Zn Species Research Articles

Probing the Nature of Zinc in Copper‐Zinc‐Zirconium Catalysts by Operando Spectroscopies for CO2 Hydrogenation to Methanol

AbstractActive Zn species in Cu‐based methanol synthesis catalysts have not been clearly identified yet due to their complex nature and dynamic structural changes during reactions. Herein, atomically dispersed Zn on ZrO2 support is established in Cu‐based catalysts by separating Zn and Zr components from Cu (Cu−ZnZr) via the double‐nozzle flame spray pyrolysis (DFSP) method. It exhibits superiority in methanol selectivity and yield compared to those with Cu−ZnO interface and isolated ZnO nanoparticles. Operando X‐ray absorption spectroscopy (XAS) reveals that the atomically dispersed Zn species are induced during the reaction due to the strengthened Zn−Zr interaction. They can suppress formate decomposition to CO and decrease the H2 dissociation energy, shifting the reaction to methanol production. This work enlightens the rational design of unique Zn species by regulating coordination environments and offers a new perspective for exploring complex interactions in multi‐component catalysts.

Conversion of lignite-derived volatiles into aromatics over Zn@MCM-41 and ZSM-5 tandem catalysts with a high stability

Direct conversion of lignite into light aromatics via catalytic fast pyrolysis is a great challenge because of severe catalyst deactivation and low aromatics yield. The tandem catalysis (1Zn@MCM-41 and ZSM-5) system was employed to promote the conversion of thermally-derived volatiles of lignite into aromatics at 600 °C. The mesoporous Zn-incorporated MCM-41 (xZn@MCM-41) with different doping amount of Zn was prepared with a one-pot hydrothermal procedure. The structure and the dispersion of Zn species of 1Zn@MCM-41 were systematically studied with XRD, SEM, BET, NH3-TPD and so on. The presence of 1Zn@MCM-41 significantly expands the lifetime of the microporous ZSM-5. Meanwhile, the yield of aromatics, especially benzene, is also increased to some extent. The content of the long-chain hydrocarbons and the phenolic compounds are decreased significantly after being cracked by the mesoporous 1Zn@MCM-41. More small molecules are able to contact with the active sites located in the micropores of ZSM-5 with the presence of Zn@MCM-41. In addition, the ZSM-5 in the tandem catalysts system presents an excellent stability. Therefore, this meso-microporous tandem catalysis system promotes the preferential cracking of macromolecular compounds, the cracked small molecules generated from which then contact with ZSM-5 to produce aromatics. This work provides a new perspective for the gradient catalyzing lignite-derived volatiles over a tandem catalysis system.

Active species identification in Zn and Mn-based materials for application in alcohol oxidation reactions

Surface and bulk properties and catalytic performance during benzaldehyde synthesis of inexpensive Zn modified-MnCO3 catalysts (xZnMn), prepared by impregnation method and covering a wide range of Zn loadings (1.0 wt% Zn < x < 22.6 wt% Zn) were deeply investigated for the first time. XRD, TPN2 (temperature-programmed decompositions in N2) and XPS characterization showed that different crystalline phases containing Mn and/or Zn species are present in xZnMn. In these phases Mn oxidation state changes from 2+ toward higher values (3+ and 4+ ) as Zn content increases entailing the transformation of MnCO3 to ZnMn2O4 spinel and MnOx oxides.During benzyl alcohol oxidation at mild reaction conditions using oxygen, the highest benzaldehyde yield (∼70 %) was obtained on 15.4ZnMn sample after 6 h of reaction. The superior catalytic performance of the 15.4ZnMn catalyst was attributed to a synergistic interaction of both metals.

Room-temperature photosynthesis of Zn(i) compounds with high air stability

We found two Zn(ii) compounds with similar metalloviologen structures that, upon being exposed to light at room temperature in air, generated Zn(i) species.

Rapid precipitation-free synthesis of zinc oxide nanowire arrays

The microwave-assisted hydrothermal method is cost-effective for rapidly producing zinc oxide (ZnO) nanowire array. However, microwave-assisted heating can make many bulk crystals that may contaminate the nanowire array. The precipitated contamination on the ZnO nanowire array formed using the microwave-assisted hydrothermal method is grossly underreported in the literature. ZnO is usually prepared in a high basic condition to reduce the bulk nucleation, using ammonia or amine complexes. As microwave-assisted synthesis is preferred in open reactors to avoid high-pressure development and design complexity, amine-based components are particularly unsuitable for such reactions due to high volatility. In this work, the ZnO nanowire array was synthesized using the microwave-assisted hydrothermal method in an open reactor using a basic non-volatile compound, Sodium hydroxide (NaOH). Rapid growth of ZnO nanowires was achieved at a rate of 4.6 μm/h without having precipitated materials using NaOH. In contrast, ammonia-assisted synthesis showed a large number of precipitates on the array. High and low-magnified field emission scanning electron microscopy images revealed the formation of pristine ZnO nanowires and debris/contaminant-free arrays using a non-volatile hydrolyzing agent. Speciation data shows that various ionic species of Zn under different basic conditions using ammonia and NaOH can control the bulk nucleation of ZnO.

Quantitative 67Zn, 27Al and 1H MAS NMR spectroscopy for the characterization of Zn species in ZSM-5 catalysts.

67Zn MAS NMR spectroscopy was used to characterize the state of Zn in Zn-modified zeolites ZSM-5. Two 67Zn enriched zeolite samples were prepared: by solid-state exchange with metal 67Zn (Zn2+/ZSM-5 sample) and by ion exchange with zinc formate solution (ZnO/H-ZSM-5 sample), both containing ca. 3.8 wt% Zn. The elemental analysis, TEM, and quantitative BAS and aluminum analyses with 1H and 27Al MAS NMR have shown that Zn2+/ZSM-5 contains zinc in the form of Zn2+ cations, while both ZnO species and Zn2+ cations are present in ZnO/H-ZSM-5 besides BAS. 67Zn MAS NMR has detected the signal of Zn in a tetrahedral environment from ZnO species for both the activated and hydrated ZnO/H-ZSM-5 zeolite. The signal of Zn in an octahedral environment was detected for the hydrated Zn2+/ZSM-5 and ZnO/H-ZSM-5 zeolites. This signal may belong to zinc cation [HOZn]+ or Zn(OH)2 species surrounded by water molecules. Quantitative 67Zn MAS NMR analysis has shown that only 27 and 38% of zinc loaded in the zeolite is visible for the activated and hydrated ZnO/H-ZSM-5 zeolite, and 24% of Zn is visible for the hydrated Zn2+/ZSM-5. Zinc in the form of ZnO species is entirely visible in both the activated and hydrated ZnO/H-ZSM-5 zeolite, while Zn2+ cations are not detected at all for the activated sample and only 29% of Zn2+ cations is visible for the hydrated zeolite. Detection of only a part of Zn2+ cations in the form of [HOZn]+ or Zn(OH)2 species in octahedral environment presumes only partial hydrolysis of the bond of Zn2+ cation with framework oxygen and further solvation of the Zn species formed at hydrolysis by the adsorbed water.

Organic Wastes Augment the Eco-Restoration Potential of Bamboo Species on Fly Ash-Degraded Land: A Field Study

Rapid industrialization has been a major cause of land degradation and other environmental problems globally. Most energy inputs in industries depend on coal-burning power stations which release various pollutants into the environment. Among these pollutants, fly ash is a concerning pollutant for soil quality, as it occupies a voluminous area of land in India and renders it unproductive. Therefore, this work attempts to evaluate the organic amendment-facilitated bioremediation/phytoremediation of fly ash-degraded land through bamboo plantations under field conditions. Three species of bamboo, Bambusa balcooa, B. tulda, and B. bambos, were planted on fly ash dumpsite soil amended with a combined dose of pressmud and farmyard manure. Results demonstrate that after two years of plantation, all the physicochemical attributes of the degraded land were improved considerably compared to the initial observations. Although all the bamboo species exhibited promising phytoremediation potential, variations were observed in their phytoremediation mechanisms: B. balcooa was the most ideal phytostabilizer species for Cu, Zn, and Ni. B. bambos was found as an ideal phytostabilizer of Pb and Zn while B. tulda was found as a phytoextractor of Cr and Zn. Additionally, all the bamboo species sequestrated atmospheric CO2 considerably, resulting in overall environmental restoration of the degraded area; B. balcooa was the most ideal species. Moreover, B. balcooa exhibited the highest air pollution tolerance index compared to other species. This study, therefore, recommends that a comprehensive analysis of organic matter-mediated phytoremediation would assist environmental managers to formulate sustainable eco-restoration strategies, ensuring a sustainable solution to land degradation.

Constructing self-assembled microtubular structured Zn–In–S and modulation mechanism towards efficient photocatalytic degradation of tetracycline

The accumulation of antibiotics in the environment has caused worldwide concern and photocatalytic processes have shown attractive prospects for the elimination of antibiotics due to its sustainability, cleanliness and efficiency. In this study, a series of self-assembled hollow tubular Zn–In–S photocatalysts (Zn-doped In2S3, ZnIn2S4, and ZnS/ZnIn2S4) were first designed by one-step sulfidation of Zn/In-MOFs. The as-synthesized microtubular structured Zn–In–S exhibited high surface area(107.61–127.26 m2/g), high porosity(0.25–0.52 cm3 g−1) and high degradation rate(≥86%) towards tetracycline within 120 min. Moreover, the photoelectric properties and photocatalytic performance were dependent on the existence of Zn species. Particularly, the optimized hollow microtubular ZnS/ZnIn2S4 composites exhibited ultrahigh photocatalytic degradation rate (>90%) within 1 h solar light irradiation. The kinetic constant reached 0.0379 min−1, which was 2.96, 2.02, and 5.65 times higher than In2S3, ZnIn2S4, and ZnS respectively. The ultrahigh photocatalytic degradation efficiency originated from the formation of direct Z scheme heterojunction between ZnIn2S4 and ZnS. The unique heterojunction enabled the effective separation of electron-hole pairs and the production of highly reactive oxidants (•OH, •O2−, h+). Density functional theory(DFT) demonstrated a higher charge density near the Fermi level and higher affinity towards O2 molecules, which contributed to the efficient interfacial charge mobility and O2 activation. The work provides guidance for the modulation of ternary catalysts to maximize the virtues of photocatalytic activity.

Synergistic effects of the Se and Zn supplemental combination on the nutrient improvement of mannitol and adenosine and the multi-element bioaccessibility in Cordyceps cicadae

Cordyceps cicadae is an edible mushroom. Selenium (Se) and zinc (Zn) are essential microelements for humans. To develop Se–Zn biofortification strategies for C. cicadae, the effects of three Se species (selenium nanoparticles, selenite, and selenate) and two Zn species (zinc sulfate and EDTA-zinc) on biomass, mineral elements, mannitol, adenosine, cordycepin, and bioaccessibility were investigated. The fruiting bodies had significant bioaccumulation and biotransformation ability for selenite, which converted selenium nanoparticles, selenite, and selenate into selenocysteine (63.5–70.2%) and selenomethionine (20.4–27.7%). Selenite and selenate eliminated inhibition of fruiting bodies growth by zinc. The synthesis of mannitol and adenosine was promoted by Se–Zn biofortification, while interfering with multi-elements enrichment. During gastrointestinal digestion, over 57.1% of total Se, 41.3% of essential microelements, 100% of selenomethionine, and 6.0% of selenocysteine were released. The release of adenosine and cordycepin in selenite plus zinc sulfate treatment were increased by 21.9% and 106.0% compared with control. The findings indicate that Se–Zn-enriched C. cicadae is a novel Se and Zn supplement.

Cr-Zn/Ni-Containing Nanocomposites as Effective Magnetically Recoverable Catalysts for CO2 Hydrogenation to Methanol: The Role of Metal Doping and Polymer Co-Support

CO2 hydrogenation to methanol is an important process that could solve the problem of emitted CO2 that contributes to environmental concern. Here we developed Cr-, Cr-Zn-, and Cr-Ni-containing nanocomposites based on a solid support (SiO2 or Al2O3) with embedded magnetic nanoparticles (NPs) and covered by a cross-linked pyridylphenylene polymer layer. The decomposition of Cr, Zn, and Ni precursors in the presence of supports containing magnetic oxide led to formation of amorphous metal oxides evenly distributed over the support-polymer space, together with the partial diffusion of metal species into magnetic NPs. We demonstrated the catalytic activity of Cr2O3 in the hydrogenation reaction of CO2 to methanol, which was further increased by 50% and 204% by incorporation of Ni and Zn species, respectively. The fine intermixing of metal species ensures an enhanced methanol productivity. Careful adjustment of constituent elements, e.g., catalytic metal, type of support, presence of magnetic NPs, and deposition of hydrophobic polymer layer contributes to the synergetic promotional effect required for activation of CO2 molecules as well. The results of catalytic recycle experiments revealed excellent stability of the catalysts due to protective role of hydrophobic polymer.

Re-dispersion of active Zn species on modified S-1 zeolite as an efficient catalyst for direct dehydrogenation of propane

Highly active and inexpensive catalysts for propane dehydrogenation (PDH) are required for largescale propylene production in industrial application. Compared to Pt- and Cr-based catalysts, Zn-based nanomaterial is a promising candidate due to its environmental friendliness and coking-resistant but remains a great challenge. In this study, we developed a novel multi-component structure consisting of low Pt and abundant active Zn species highly dispersed on Fe-doped S-1 zeolite as PDH catalyst. Specifically, Fe-doping in S-1 support provided anchoring sites for loading Zn species with uniform distribution. Moreover, the very small amount of Pt was applied as promoter, which is beneficial to achieve the re-dispersion of Zn species with the formation of Znδ+ and Zn2+ active sites. The resulting 0.05Pt5Zn1Fe@S-1 catalyst exhibited the outstanding performance (conversion of propane: 40%, selectivity of propylene: 85%, and yield of propylene: 31.39%) as well as satisfactory regeneration ability. This improvement can be ascribed to the synergistic coupling between Pt promoter and the highly dispersed Zn species on modified S-1 support. This study opens a new way to design efficient and stable dehydrogenation catalysts.

Tuning the Mechanism of H/D Exchange for Isobutane on H-BEA by Loading Zn Species in Zeolite.

Kinetics of H/D hydrogen exchange between deuterated isobutane-d10 and Brønsted acid sites (BAS) of three zeolite samples (H-BEA, ZnO/H-BEA, Zn2+ /H-BEA) were monitored with 1 H MAS NMR in situ at 343-468 K. The regioselective H/D exchange in the methyl groups detected on H-BEA can be rationalized in terms of the mechanism of indirect exchange, which involves protonation of the intermediate olefin and further hydride abstraction from the other alkane molecule by the formed carbenium ion. Loading of Zn species in the zeolite results in a decrease of the rate and an increase of the activation energy of the exchange. The loaded Zn species provide the tuning effect on the reaction occurrence, changing the mechanism from the indirect one to the mechanism of the direct exchange.

High specific energy and power sodium-based dual-ion supercabatteries by pseudocapacitive Ni-Zn-Mn ternary perovskite fluorides@reduced graphene oxides anodes with conversion-alloying-intercalation triple mechanisms

• A new concept of sodium-based dual-ion supercabattery (S-DICB) was firstly proposed. • The superior pseudocapacitance-dominated kinetics was verified. • The charge storage mechanism of KNZMF@rGO anode was deeply deciphered. • Utilizing different presodiated methods to explore the impact on S-DICB. Sodium (Na)-based electrochemical energy storage devices have drawn particular attention in the renewable and rechargeable energy storage system primarily because of their remarkable energy density and cost-competitive advantages. Herein, we have reported a novel ternary perovskite fluoride K 0.97 Ni 0.31 Zn 0.28 Mn 0.41 F 2.84 with a well-distributed reduced graphene oxide substrate (denoted as KNZMF@rGO) as anode for Na-ion storage that possesses the fast kinetics validated via electrochemical and density functional theory (DFT) methods as well as superior lifespan, which delivers fascinating performances owing to the unexceptionable synergistic effect of Ni, Zn and Mn redox-active species with variable valence. Meanwhile, the surface conversion, alloying and intercalation triple hybridization mechanisms of KNZMF@rGO anode have been explored by the electrochemical analysis and the diverse ex situ physicochemical characterizations. What is more, this work also offers new insights into the device design and proposes the previously unreported “sodium-based dual-ion supercabatteries” (S-DICBs) systems for establishing advanced electrochemical energy storage devices, which exhibit the more intriguing properties than traditional sodium ion capacitors (SICs) and sodium-based dual ion batteries (S-DIBs). In parallel, utilizing different presodiated current densities of anode to explore their impact on the various electrochemical properties of S-DICBs opens up a way for the research of presodiation techniques in the future. A new concept of sodium-based dual-ion supercabattery (S-DICB) was constructed via the pseudocapacitive Ni-Zn-Mn ternary perovskite fluoride (ABF 3 )@reduced graphene oxide (KNZMF@rGO) anode material, which shows the surface conversion/alloying/intercalation triple mechanisms for charge storage. The lower presodiated current density of anode leads to the higher electrochemical properties of S-DICB because of the superior solid electrolyte interface (SEI) film, charge balance and utilization rate of active substance.

Effects of short-range order on phase equilibria and opto-electronic properties of ternary alloy ZnxCd1-xTe

We employ first principles methods based on density functional theory and beyond to study ZnxCd1-xTe, 0≤x≤1, alloys in the zinc blende (B3) crystal structure. Cluster Expansion and Monte Carlo formalisms were deployed to provide a phase diagram determining consolute temperature of 387 K at 40% Zn concentration. Opto-electronic properties are computed with the hybrid HSE06 functional for disordered ZnxCd1-xTe alloys, which were simulated using special quasi-random structures. Bowing effects in the bandgap and effective carrier masses were observed in alloying which can be attributed to local geometrical distortions as portrayed by bond length distributions. Downward bowing in the electronic bandgap will be beneficial in photovoltaic applications through increased net photocurrent. Absorption coefficients show robust absorption in ZnxCd1-xTe as indicated by substantial optical absorption throughout all Zn concentrations, aided by low reflectivity that ensures a high absorption. Presence of short-range order in Zn0.25Cd0.75Te was observed through clustering and anti-clustering among different cationic species of Zn and Cd. It has a value of 0.11 at 1000 K compared to −0.79 at 400 K. The bandgap of Zn0.25Cd0.75Te at 1000 K was found to be slightly higher, 0.05 eV, than at 400 K, consistent with the value of short-range order. Thus, short-range order and possibly composition can be used in the design and synthesis of the appropriate solar cell, thereby improving the performance in this system.

Investigation of CNT and Zn doped Cu-SSZ-13 zeolite catalyst for ammonia selective catalytic reduction activity of NOx

Hybrid Cu-SSZ-13 zeolite catalyst are prepared and analyzed for NH3-SCR activity with different topologies in the present investigation. Cu-SSZ-13 was synthesized by ionexchange method, and hybrid Cu-SSZ-13 was synthesized by wet-impregnation method with three different molar ratios between Znx-CNTy as 1:5, 1:10, &amp; 1:15 and maintained as 1:5 mass ratio between Znx-CNTy/Cu-SSZ-13 hybrid zeolite catalysts. The catalytic activity measured at a temperature window of 100˚C to 550˚C concludes hybrid Zn1- CNT10/Cu-SSZ-13 catalyst exhibits high NH3-SCR performance (100%) at a temperature of 180˚C to 475˚C and by anti-sulfur activity, it exhibits 80% NOx at 300˚C for 8hrs in the presence of SO2 gas in feed aid that addition of Zn species and CNTs influence Cu-SSZ13 in NH3-SCR activity finding them to be a better catalyst for NOx reduction.

Speciation and isotopic analysis of zinc in size-fractionated aerosol samples related to its source and chemical processes

Zinc (Zn) in aerosols plays important roles for biological activity and attracts public attention from the perspective of environmental measures. Because of its high volatility and water solubility, Zn is readily released into the atmosphere by human activities and supplied to natural water. To explore the origin and formation process of Zn in atmospheric aerosols, it is important to investigate isotopic (= δ66Zn) and speciation information of Zn in size-fractioned aerosols. We measured light δ66Zn (e.g., δ66ZnIRMM = −1.32‰ as the lowest value; IRMM-3702 is used for the normalization in this study) mainly for the particles ranging from 0.65 to 4.7 μm for the samples collected at Tsukuba, Chiba, and a motorway tunnel (Yasumiyama Tunnel in Hiroshima) in particular for the samples collected in 2002, but δ66ZnIRMM in the particle sizes increased above −0.8‰ for the samples collected in 2011 and 2016. Zn species in aerosols were estimated based on X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy, suggesting that (i) Zn oxalate and sulfate and (ii) Zn oxide, sulfide, and carbonate are main Zn species in fine and coarse particles, respectively. In particular, Zn chloride was found mainly in the middle particle size range (2.1–4.7 μm), which corresponds to the range with light δ66Zn, suggesting that the light δ66Zn was caused by emission of Zn chloride during artificial combustion processes in accordance with other studies. The origins of Zn in aerosols are assumed to have three endmembers; (A) tire and brake wears and road dust, (B) industrial emissions, and (C) vehicular exhaust. Their formation mechanisms are related to vaporization and mixing processes based on the results of combined analysis of atmospheric concentration, speciation, and isotopic composition of Zn with different particle sizes. These trends could be successfully interpreted by species-specific δ66Zn values: component (A) consisting mainly of Zn oxide and sulfide with relatively heavier δ66Zn, component (B) Zn chloride and sulfate secondarily formed in the droplet mode having lightest δ66Zn among all the species, and (C) Zn oxalate with δ66Zn closer to 0‰ due to its emission by the complete combustion in vehicle engines. Species-specific Zn isotope data obtained by the simultaneous application of speciation and isotopic analyses of Zn in size-fractionated aerosols complementary provide novel information on the initial generation and secondary processes for the formation of Zn species in the aerosols.

Structure Evolution of Zn Species on Fresh, Deactivated, and Regenerated Zn/ZSM-5 Catalysts in Ethylene Aromatization

Structure Evolution of Zn Species on Fresh, Deactivated, and Regenerated Zn/ZSM-5 Catalysts in Ethylene Aromatization

Zn species decorated Pt/CeO2 catalysts for selective hydrogenation of 1,4-butynediol in continuous-flow reactor

Designing highly efficient and stable catalysts is vital for large-scale manufacturing of 1,4-butenediol via continuous-flow semi-hydrogenation of 1,4-butynediol. Herein, Zn species decorated Pt/CeO2 catalysts are investigated in the semi-hydrogenation of 1,4-butynediol. Both the Ptδ−-Znδ+ structure and the decreased Pt surface density caused by Zn decoration profoundly affect the adsorption structures and bonding strength of the reactants and intermediates, thus leading to a favorable hydrogenation property. The activation energy over PtZn0.5/CeO2 is 42.8 kJ mol−1, which is lower than 56.6 kJ mol−1 over Pt/CeO2 catalyst. The PtZn0.5/CeO2 achieves the highest 1,4-butenediol yield (85%) under mild conditions and stability in the long-term reaction (100 h). This stems from the proper spatial arrangement of Ptδ− active sites leading to a weak π-bonding mode toward CC adsorption, rather than strong di-σ adsorption at successive Pt sites. It provides fundamental guidelines for designing Pt-based catalysts with high performance for the selective hydrogenation of alkynols.

Boosting hydrogen evolution on NiFeZn electrocatalyst by defect surface modulation using alkali etching

Developing highly efficient catalysts using facile approaches is important for accelerating the slow reaction kinetics of the alkaline hydrogen evolution reaction (HER) and ensuring cost-effective hydrogen production. In this study, we reported a facile alkali etching method to boost the HER activity immediately after electrodeposition of a NiFeZn catalyst on Ti paper. During etching, (oxy)hydroxides were formed on the surface, and Zn species were etched from the deposits, which resulted in a roughened surface with more valleys generated between grains, facilitating a faster mass transport during the electrochemical reaction. The etched catalyst exhibited a boosted HER overpotential of 57 mV at −10 mA/cm2 and accelerated HER kinetic with Tafel slope of 97 mV/dec compared with that of the pristine catalyst. Our results demonstrated an efficient approach for boosting the catalyst activity in the alkaline HER.

Enhanced reducibility of well-defined Cr oxide nanostructures on Au(111) through Zn doping

Mixed oxides play important roles in many heterogeneous catalytic processes, and understanding of interaction between different oxide components is crucial for synthesizing the catalysts with high performances. Here, we introduce trace of metallic Zn species into well-defined chromium oxide (Cr oxide) nanostructures grown on Au(111) including CrO2-bilayer nanoislands and Cr2O7dinuclear clusters and study the impact of the dopant on reducibility of the Cr oxides. Combining low-temperature scanning tunneling microscopy (LT-STM) and X-ray photoelectron spectroscopy (XPS), we demonstrate that incorporation of 2.5 at.% Zn can lower the initial reduction temperature of Cr oxides by 70–160 K upon heating in ultrahigh vacuum. The reduction degree of Zn-doped Cr oxide is much larger than the pure oxide at the same heating temperature. Density functional theory (DFT) calculations reveal that the enhanced reducibility of the pristine oxide via introduction of Zn dopant mainly comes from the promoted activity of oxygen atoms due to Zn substitution of surface Cr.